Open-end spinning devices of the above described type are known, e.g., from German Patent Publication DE 196 17 527 A1. In this spinning device, a pivotably mounted cover element has an annular groove for receiving a lip sealing element and is also formed with a receptacle with conical contact surfaces opening in the direction of the rotor housing in which a correspondingly conical conduit plate adapter is detachably fixed. The precise angular fitting position of the conduit plate adapter is achieved by a positioning device consisting of a centering pin and an arced groove. The maintenance of the prescribed angular position of the conduit plate adapter in the fiber conduit plate can be monitored via a monitoring device. In the assembled state the conduit plate adapter, aligned in a precise angular manner by the centering pin, rests by its conical contact surface on the correspondingly formed conical contact surface of the receptacle and is loaded thereby with a holding force acting in axial direction via jointly acting, positive fastening means and frictionally connected or frictionally engaged means.
In this known device, the described type of fastening is disadvantageous. In order to replace the conduit plate adapter, in addition to disengaging the frictionally connected means, e.g., a magnetic coupling, the positive fastening means, e.g., designed as a threaded connection or bayonet catch and cooperating with the magnetic coupling, must always be disengaged, using a special tool if necessary.